Insight into SnO₂-based gas-sensitive materials and readout circuits for semiconductor gas sensors

The advent of SnO₂ materials has significantly revolutionized semiconductor gas sensors. However, their high working temperature, sluggish response/recovery velocities, poor sensitivities, and baseline drift are still essentials factor impeding their applications in advanced sensing devices. Owing to the improved receptor, transducer, and utility factor function, constructing heterostructures substantially enhances the gas-sensitive properties of single material. Although many works on SnO₂ materials have been summarized in some excellent reviews, a comprehensive overview of SnO₂ materials from the underlying gas-sensitive mechanisms to material design to applications combined with back-end detection circuits is missing. Herein, a comprehensive review is presented on the state-of-art of SnO₂-baesed p - n heterostructures and applications of the combination of back-end detection circuits and devices. The microscopic regulation mechanism of p - n heterojunctions on improved gas-sensitive properties is investigated in depth. Some representative composites are discussed, including SnO₂ composited with metal oxides, two-dimensional materials, and conductive polymers. Additionally, the particular emphasis is given to the detection circuits used in semiconductor gas sensors. Finally, the current challenges are summarized, and perspectives on future opportunities are presented. This work aims to advance the evolution of high-performance sensitive nanomaterials and detection circuits, and render them promising in miniaturized and integrated gas sensors.